An essential function in the operation of a personal transportation service, e.g. an elevator system, is call input and the related control of the movement of transportation devices. For example, in an elevator system call input has traditionally been arranged by providing each floor with up-down call buttons, by means of which an arriving elevator customer indicates a desired traveling direction. In addition, the elevator car has to be provided with a control panel tailored for the place of installation of the elevator system and comprising a button for each floor, of which the elevator passenger presses the one corresponding to his/her destination floor. Thus, in the traditional call input method, the elevator customer has to enter two calls. First, an elevator has to be called by one press of a call button to the floor where the customer is located. In addition to this, a second press of a call button is needed in the elevator car.
A call input method whereby the elevator passenger selects his/her destination floor while still in the elevator lobby outside the elevator is called destination allocation. In destination floor elevator systems, each passenger wishing to have a ride on an elevator gives on the landing his/her destination floor to which this passenger is traveling by elevator. Thus, the number of calls to be input per elevator trip in destination floor elevator systems is one instead of the earlier two calls.
The destination floor is given e.g. by using a destination call device specially reserved for this purpose, which device is an extended version of the landing call button and is mounted at the landing. In the destination call device, the actual landing call button has been extended with a more comprehensive user interface such that the user, i.e. elevator passenger, can indicate the floor to which he/she wishes to ride on an elevator. The destination call device may also be a passenger terminal device designed for this purpose or it may be e.g. the user's own mobile phone.
The destination call is sent to the elevator control system for elevator allocation. The elevator control system receives the call and tries to decide which one of the elevators in the elevator group can best serve the person having entered the call. In response to the destination call sent by it, the passenger terminal device receives information from the elevator control system regarding the elevator serving the call. The information received by the user may comprise e.g. information as to which one of the elevators has been allocated to the user and where it is located relative to the user. The information may additionally comprise an estimated waiting time or it may be a signal announcing the arrival of the allocated elevator at the floor of departure.
In the case of automated transportation systems, such as elevator systems, it is almost impossible for the service user him/herself to influence the selection of the transportation device. When the user gives his/her destination floor, the elevator control system allocates to the user the elevator most suitable from the point of view of the elevator system and guides the passenger to this elevator. In the prior-art destination floor elevator system, each passenger traveling on the elevator must independently inform the destination floor elevator system as to his/her own destination floor. This means that each passenger has to wait independently for his/her own elevator expressly allocated to him/her, even if the passenger would like to have his/her ride on another elevator going in the same direction. Thus, there arises the problem of how the users could themselves stop an elevator going past the floor and have a ride on it to the destination floor.
On the other hand, if passengers do not await the elevator allocated to them but select another elevator, then the elevator system receives incomplete information as to which elevator the passenger actually uses to travel to a given destination floor. The incomplete information received by the destination floor elevator system and especially its control system leads to a reduction in the level of service provided by the elevator system to the passengers. It is obvious that, if it were possible for the elevator system to offer the user more than one alternative as an allocated elevator, the elevators and elevator system could provide better service to the passengers.
Moreover, the information provided by the system regarding the elevator allocated to the user may be in a form difficult to understand, in which case the user will find the instructions given by the system unclear and difficult to follow. The user may also get frustrated waiting for the elevator he/she has been instructed to use, particularly if another elevator stops at the floor before the elevator intended for the user.
In prior-art solutions, a fundamental problem is that the user is not given a possibility to have a say on the selection of an elevator according to his/her own personal needs. In existing transportation systems, the user needing the service can not be offered the best transportation means selected according to his/her personal requirements, but the user has to travel on the elevator allocated to him/her by the elevator system. The user might e.g. want to ride on an elevator that provides a total traveling time as short as possible. Alternatively, the user might prefer to select an elevator that provides a total traveling time as short as possible or the user might want to travel on a panoramic elevator.